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Small Scale Processing of Oilfruits and Oilseeds (GTZ, 1989, 100 p.)

2. Target Groups and Technologies

2.1 Family level

(introduction...)

2.1.1 Oil palm fruit

2.1.2 Oil seeds

2.2 Village level

(introduction...)

2.2.1 Oil palm fruit

2.2.2 Oil seeds

2.3 District level

Small Scale Processing of Oilfruits and Oilseeds (GTZ, 1989, 100 p.)

2. Target Groups and Technologies

2.1 Family level

In most societies, the family comprises the smallest economic
unit. In developing countries, however, a family does not usually consist simply
of husband, wife and their children. More often, a family includes other
relatives (grandparents, grandchildren, cousins, etc.) or even close friends
living in the same household. In islamic countries, a family might include a
second or more wives and their children. In traditionally oriented societies,
the extended family is still very important for the social identity of the
individual.

Viewed from the point of oil processing, a family is defined
here as a group of people living together in one household, ranging in numbers
from one (exceptionally) up to 30, sharing common social and economic interests
and usually having their meals together. Oil processing at this level of social
aggregation primarily aims at subsistence needs, but also contributes to cash
income.

In many areas of developing countries, oil fruits and oil seeds
are available as a rawmaterial, and processes to prepare vegetable oil are known
to the population. The modest needs for vegetable oil for the family pot are
supplied by the women, following traditional methods of processing.

Next to the production of oil for the family, women also make
products for sale on the local market to earn the money required to pay for
their contributions to other family needs, such as the ingredients for the daily
family pot. These are generally made up by some vegetables and spices and, when
the money is available, by some (dried) fish or meat, all prepared into a sauce.
This sauce is eaten as a relish, that accompanies the staple, which is based on
a starchy food as a grain or a root crop.

When men produce an oilcrop that must be processed before
marketing, the processing is generally not carried out at the family level. When
sizable quantities are involved, the processing is carried out by specialized
groups at the village level. This will be dealt with in the next chapter.

Below, a description is given of some traditional methods at
family level to process oil palm fruit and oil seeds for food and cash
income.

2.1.1 Oil palm fruit

(see Flowsheet 1)

The semi-wild palms are mainly of the dura" variety. The
aura fruit contains large nuts with a thick outer shell. Around the nut is a
relatively thin layer of oilcontaining fruit pulp.

Flowsheet 1 Traditional Process for
Oil Palm Fruit

Women search for fruits that have dropped out of the bunches
from the trees or buy loose fruit at the market. Women do not climb palms and
thus can only obtain bunches of fruit that have been cut by the men. Women can
pay men to climb the trees and cut the bunches. Bunches have to be stripped to
obtain the fruit.

The fruit can be more easily separated from the bunches after
fermentation in a heap for 3-4 days. To facilitate the separation the bunches
can be cut in small clusters before fermentation.

The fruit is cooked and subsequently pounded using mortar and
pestle. When larger quantities are to be processed, in some areas, the fruit is
pounded using a halved drum and a large number of pestles or the fruit is mashed
by trampling with the feet in a pit. Men can assist with the stripping of the
bunches and the mashing of the fruit. After crushing by pounding or trampling,
the mass of fruit pulp and nuts is mixed with excess water. The nuts are washed
free from pulp and are allowed to settle to the bottom. The fibres are then
thoroughly washed with water and finally pressed out by hand to remove all oil
and oil-containing cell material.

In some areas just the floating cream is collected, whereas in
others all the liquid that remains after removal of the nuts is taken. This mass
is transferred to a drum and boiled for a few hours. The palm oil at the top is
skimmed off and finally purified and dried by heating in a separate pot. The
remaining sludge is sometimes concentrated by boiling and used for food.

The nuts are spread on the ground and dried in the sun, after
which they are cracked to obtain the kernel, traditionally by tapping between
stones. The fibre is also dried and used as a combustible.

The required time reported for processing one drum (44 gallons
or 2001), containing around 150 kg of palmfruit, is on the average 24 and 32 man
working hours respectively for Benin and Gambia.

Oil recovery out of a drum varies between 9 kg for aura' oil
palm fruit in Gambia, about 15 kg for aura fruit in other countries and as much
as 20 kg for a aura! tenera (improved variety) mixture in Cameroon.

Traditionally, the fruit could be left to ferment for days,
making the processing quite easy. However, this oil contains a high percentage
of free fatty acids and has a sharp taste. It is therefore known as hard"
oil.

Possibilities for improvement

In principle the traditional method for processing oil palm
fruit is based on the separation of the oil-containing cell material from the
nuts and the fibre followed by the extraction of the oil from the cells by
prolonged cooking. This process has a limited oil recovery and requires much
water and energy.

These drawbacks can only be overcome by changing to a process
that uses practically no water but demands thorough preparation of the fruit,
before the oil can be extracted with a hand press.

Since such a system requires much more investment than the
traditional process, it is not a feasible proposition at the family level. Only
at village level can the investments be justified either in the form of a
service system, to be used by processors against a fee' or as an asset of a
specialized informal or formal co-operative. Details of the processes are given
under
2.2.1.

2.1.2 Oil seeds

2. By pounding, crushing between stones or a stone and an iron
bar or by the service mill; fresh coconut is grated.

3. Groundnut paste is treated by stirring and addition of some
water (12 %). Crushed palm kernels are cooked in excess water. Shea nut paste is
treated by beating in air and washing of the cream or cooking in excess water.

4. Tunkusa and kuli-kuli for human consumption from groundnuts;
animal feed from palm kernels and coconuts.

Groundnuts

Groundnuts are almost exclusively processed in combination with
the utilization of the residue for human consumption. In fact often the
by-product, a kind of a snack, has to be understood to be the main product and
the manufacturing of the groundnut oil only as part of the process.

In Ghana the following process was observed:

- decorticated groundnuts are roasted, treated by a rubbing
action and winnowed to remove the pellicles- the nuts are crushed between
stones, several times to obtain a fine paste- this paste is stirred
vigorously, while gradually adding some hot and/or cold water (about 10 %
w/w)- when the oil appears it is skimmed off and the mass formed into large
balls and some more oil is pressed out by hand; the balls are called:
tunkusa- the tunkusa is subsequently processed into kuli-kuli, a ring or
ball-shaped snack, prepared by frying products moulded out of tunkusa in
groundnut oil. It can also be used as the main ingredient for groundnut
soup".

For Burkina Faso, a similar process has been described.

A typical example has shown a recovery of 0.5 kg oil and 3.5 kg
kuli-kuli (out of 3.8 kg tunkusa) from 4.0 kg of groundnuts; the production of
the oil and tunkusa took 5 man working hours.

Palm kernel

After cracking the palmnuts, the palm kernels can be separated
out. Traditionally they are processed into an oil after roasting. The roasting
makes the palm kernels brittle and more easy to crush by pounding. However, the
quality of the oil deteriorates because of the temperature and the oil becomes
dark coloured. After roasting the kernels are pounded. Then the pounded mass is
mixed into excess water and boiled for hours, during which the oil is skimmed
off. Finally the oil is dried by heating. 18 kg of palm kernels give I gallon or
4 kg of oil in about 12 man working hours.

Coconut

The basic way to process fresh coconut is to cut the coconut
lengthwise in half and to remove the white kernel or so-called 'meat'. The meat
is first grated on a grating surface by hand then mixed with water and pressed
out by hand or foot. This procedure is repeated several times. The coconut milk
obtained is left to stand for a few hours to permit the separation into a
supernating oil-containing cream and water. Subsequently the cream is collected
and transferred into a cooking pot and heated under continuous stirring to dry
the oil by boiling. The protein in the cream coagulates and dries. The oil is
filtered. The residue can be eaten as a snack.

Shea nut

Also shea nuts are processed following a wet process. This
process has been studied in Mali and includes:

- drying and roasting of the nuts - decorticating of the
nuts- pounding of the shelled nuts into a liquid mass, that contains
particles smaller than about 3 mm- crushing of the mass into a very fine
paste between stones or a stone and a metal bar- in some areas the brown
paste obtained is mixed into water, and air is brought in by beating, a cream
appears; this cream is washed several times to remove all brown particles and
transferred into a cooking pot; the cream is heated until the oil is collected
at the top; the oil is skimmed off- in other areas or later in the year the
brown paste is mixed into boiling water and boiled for an hour, after which the
oil is skimmed off; more water is added and boiling continued; finally, a second
layer of oil is skimmed off- by the next day the oil has hardened into a
fat, and can be packed in leaves.

The time required for processing (grinding and oil extraction)
of 12 kg shea kernels was found to be at least 18 man working hours, of which 14
hours were required for grinding. Generally, however, much more time is needed.
Oil recoveries depend on the quality of the nuts and the skills of the women and
can range from 20 % to more than 40 % on kernel weight. Normal yields have been
reported to be between 20 and 30 %. In South Mali, recovery rates of 34 to 41 %
have been reported recently.

Possibilities for improvement

Traditional methods make use of readily available utensils as a
pounding mortar, crushing stones, calabashes and cooking pots. As they all apply
water to assist the separation of the oil, these methods have in common that
crushing of the seed into a very fine paste is essential. This stage is the most
time consuming and exhausting one. This drawback of traditional methods can only
be overcome by crushing using mechanical means. Such means, as motorized mills,
require considerable investment and are only feasible at the village level. In
fact they are already available in many villages in the form of so-called
service mills".

The only way to avoid the use of a motorized mill is to change
to a complete dry process using a hand press. During this process the seed is
treated before pressing with care, by crushing into flakes, moistening and
heating, in order to make the oil available so that it can easily be extracted
by pressing.

The equipment to be used is unsophisticated and sturdy. However,
investments required are only feasible at the village level. The process will be
treated in detail under
2.2.2.

2.2 Village level

In most rural areas of developing countries, the village is not
just a conglomeration of huts and houses but still a functioning community with
traditional cultural values and, to a certain extent - common economic
interests. Within a village, people might often or regularly come together to do
work which is more easily or more effectively done in a sizable group than
individually or with family members.

Referring to oil processing at village level, the need either
for a specialized trade or for the people to cooperate in groups arises when the
quantities to be processed become larger. In West Africa, one comes across
groups, processing oilpalm fruit, mainly consisting of women. On the Indian
subcontinent, one will find the village oil man, operating his animal drawn
gahni for the processing of oil seeds. These systems are generally operated on~a
service basis as so-called service mills", processing the rawmaterials for
the client against payment in cash or in kind:

In case the quantities concerned guarantee enough supply,
investments in equipment with improved oil recovery or with a labour saving
effect can become profitable. The ownership of this improved technology is
usually in the hands of individuals, but in the framework of development
efforts, self-help groups, pre-cooperatives and more formal cooperatives have
been encouraged to establish oil processing units.

However, as mechanized equipment tends to be dominated by men, a
shift from processing activities from many women, who are the traditional
processors, to a few men can be the result. To make it possible for women to
stay in business, the emphasis in recent years in improving traditional
technologies has been put on hand-operated equipment.

Below, the existing and possible systems for the processing of
oil crops at the village level are
presented.

2.2.1 Oil palm fruit

(see Flowsheet 1)

In West Africa, specialized groups can be found when larger
quantities of oil palm fruit have to be processed. These groups are well
organized and have been reported to be able to process 3-6 drums (450-900 kg) of
fruit per day, using traditional methods.

Handpresses

The main drawback of the traditional process with its large
water consumption, has been eliminated by the use of presses. These were
initially modified wine presses, e.g. the so-called Duchscher" curb press,
which was at one time built in Luxembourg.

Figure 9: Duchscher Curb Press

Only in Nigeria were these presses made available as privately
owned service mills all over the country. The owner of the fruit could come with
his fruit and his crew to use the equipment of the mill (as boiling drums,
pounding mortar, the press and a clarification drum) or he could bring the fruit
to have it processed by the mill. In this last case the owner of the mill would
process the fruit with his family. Later on hydraulic presses were introduced
but not accepted.

Elsewhere, groups working in the field of Appropriate
Technology, took up the design of presses to be manufactured from locally
available materials. These groups are for example TCC (Technology Consultancy
Centre, Kumasi, Ghana), who designed a press with the spindle in the centre, and
ENDA (Environnement et Developpement du Tiers Monde, Dakar, Senegal), who
adopted an already existing design for dissemination. Other countries from which
activities have been reported are Cameroon, Liberia, Sierra Leone, and Togo.

Hand presses make the traditional process simpler (see Flowsheet
3). However, the need for intensive pounding remains. In order to facilitate the
pounding step, KIT (Koninklijk Instituut voor de Tropen, Amsterdam, the
Netherlands) has introduced the reheating step, during which the fruit pulp is
completely digested. Pounding is only required to remove the pulp from the nuts.
The actual digesting of the fruit is carried out by steaming, during which the
cell walls are weakened, the protein in the cells denatured and the micro
oildroplets, as originally present in the cells, combined to larger droplets,
which are more easily pressed out.

Flowsheet 3 Usual Process for Oil Palm
Fruit with Hand Press

1 Steaming is advised to prevent the decomposition of
intercellular cement.2 Pounding can be mechanized for example with the TTC
palm fruit pounder.3 To be carried out with any press, sturdy enough to
press mixtures of nuts and fibre (see 5.1).

A complete process has been designed, starting with the steam
sterilization of the bunches to the final drying of the oil, to improve upon its
storage properties. When the fruit is cooked in water, the intercellular cement
dissolves, giving a suspension of cells (still intact), from which it is
difficult to obtain the oil. This problem is avoided by the designed steam
sterilization process. To be able to process aura oil palm fruit with a good
recovery, fibre has to be recycled and mixed into the mass to be pressed, to
prevent the nuts from touching. As the ratio of fruit pulp to nuts in Tenera
fruit is higher, it can be processed without recycling the fibre. However, to
obtain maximum oil recovery, it is recommended to reheat and press the fibre (or
the fibre/nut mixture) a second time. The complete process, including all
process steps, is presented as Flowsheet 4. With this process it is possible to
keep apart small quantities to be processed separately; an advantage, because
generally women do not want to have their own fruit mixed with that of others.

Flowsheet 4 KIT Process for Oil Palm
Fruit with Hand Press

1 When processing aura oil palm fruit it is advisable to reheat
the recirculated fibre. This is, however, sometimes very complicated. In that
case the fibre can be mixed in immediately before pressing. When processing
Tenera oil palm fruit reheating is required in case the fibre (or fibre/nut
mixture) is reprocessed.

2 When processing aura oil palm fruit, recirculation of fibre is
required to prevent the nuts from touching.

3 To be carried out whith any press, sturdy enough to press
mixtures of nuts and fibre.

Details on an oil palm processing project in Togo using this
system are given in Chapter 3.

Although the KIT process can improve much upon the oil recovery,
this process is not appreciated everywhere. Some reasons are:

- the large quantity of fibre to be recirculated in the case of
fruit with an extremely low pulp content;- the loss of the possibility to
obtain a valuable sludge to be used for food.

To overcome these drawbacks, while still improving workload and
oil recovery, a semi-traditional process was introduced for instance in The
Gambia and Guine Bissau. It includes the traditional separation of fibre,
oil-containing cream and nuts in water. The fibrous material however is
subsequently steam-heated and pressed. The cream is boiled for oil and sludge,
as traditionally.

Mechanized systems

Mechanized systems become feasible when really large quantities
are involved and regular processing is possible. The first step to be mechanized
is the pounding. TCC has developed a horizontal mechanically-driven pounding
machine (see Figure 10). This machine is continuously operated by feeding cooked
fruit at one side. Digested fruit, ready for pressing, is produced at the other.
The capacity of the pounding machine is 100 kg per hour. TCC supplies a steam
sterilization kettle and a clarification kettle as well.

Figure 10: Palm Fruit Pounder (TCC)

The nominal capacity of the TCC system, equipped with a steam
sterilization kettle, a pounding machine and two hand presses is 600 kg tenera
fruit per day (giving about 144 kg or 24 % of oil). It can be estimated that at
least 8 women are required, the equivalent of 8x8 working hours.

Even more than 40 years ago, the French firm Pressoirs
Colin" developed a continuously working press that carried out the actions of
digesting and pressing at the same time. This press was originally meant to be
operated by two men. However, it has appeared to be far too heavy for continuous
manual operation. When engine driven, this press is an interesting possibility,
particularly for the processing of tenera fruit on a relatively large scale. In
Cameroon, APICA developed a press, based on the same principles. This press is
called the CALTECH" (see Figure 11).

Figure 11: CALTECH Oil Press (APICA)
(manual version)

APICA started with a manual version. This press appeared much
too heavy as well. It could not be operated by the same men for more than half
an hour. Its nominal capacity is 100 kg per hour. The motorized version (2.3 hp
= 1.7 kW) has a capacity of 200 kg per hour. The motorized version of the
COLIN" press, presently on the market as the press SPEICHIM M-10 (4.5 hp =
3.3 kW) has a nominal capacity of 300 kg per hour.

Oil recoveries, reported for the traditional process, the KIT
process, the CALTECH and the COLIN expeller, are given in Table 8.

2.2.2 Oil seeds

The service mill

In West Africa, oil seeds are generally processed to sell the
product on the weekly market. In that case it is a great advantage, if a
reasonable quantity can be processed at any one time. This is possible by using
the services of the local grain mill, which operates on the principle of a
rotating disc. As discussed above, the crushing stage in the traditional process
is the most labour-intensive and exhausting one. A women processor can have her
oilseed crushed for a fee, if a grain mill is available and if the miller is
prepared to crush the oilseed concerned (which is not always the case, because
the mill becomes dirty with sticky material). A drawback is of course that a
great deal of the added value has to be paid to the miller.

A typical example is the groundnut processing into oil and
tunkusa (see 2.1.2). It was observed that a quantity of 18.1 kg shelled
groundnuts was processed into 3.7 kg oil and 15.7 kg tunkusa (giving 14.6 kg
kuli-kuli) by 3 women in only 8 working hours, using the service mill for
grinding the groundnuts. Crushing by hand would have required about 20 hours
alone. Service mills of the type suitable for grinding oilseed can be found over
the whole of West Africa. Oil seeds which can be crushed in such mills include:
groundnuts, palm kernels, and shea nuts. Coconut can be grated by service mills
equipped with a grater.

The use of mechanized size reduction replaces not only heavy and
exhausting work, but also improves oil recovery, as a much larger number of
oil-containing cells are opened to produce oil.

The ghani

On the Indian subcontinent, one will come across the ghani oil
mill as the village level processing system.

The ghani consists of a mortar and pestle in which the seed is
crushed. Pulverization and oil expression are carried out at the same time by
rubbing the seed between the pestle and the wall of the mortar. Water has to be
added to realize a preparation process, called cooking", by which the oil
emulsion in the cells is broken, and the micro oil droplets are combined into
larger ones. The ghani process requires much mechanical energy. A ghani operated
by one bullock (the equivalent of 0.35 kW) can process 5 kg oilseed in about one
hour. Hence, 0.35/5 or 0.07 kWh are required to process I kg of an oilseed into
oil. This energy consumption is about equal to the maximum amount of energy
required by small oil expellers.

(Oil expellers require between 1.5 and 2.5 kW to process 35 kg
of an oilseed per hour, or between 0.04 and 0.07 kWh per kg oilseed.)

Figure 12: Power Ghani

Besides, the ghani requires a lot of maintenance and repair, as
the surfaces of the mortar and the pestle suffer much abrasion. The mortar can
be recut 2-3 times but has then to be replaced. The pestle needs to be replaced
at regular intervals as well. Every 48 hours these surfaces should be checked on
wear. Also the bearing at the top has to be checked regularly.

The introduction of a mechanized version into Tanzania, the
so-called "power ghani" has had disappointing results, since special skills seem
to be required for their operation and maintenance. In India, these mechanized
versions are quickly replacing the original animal-driven ones. Also modernized
versions are available, equipped with a turning mortar instead of a turning
pestle as is the case with the traditional ghani. Ghani oil is highly
appreciated because of its special flavour, particularly in the case of mustard
seed oil.

The hand press

Although the wet process can be improved by mechanized size
reduction using a motorized disc-mill or a motorized grater, it can be of
advantage to introduce the dry process, using a hand press.

Figure

Figure 13: Palm Nut Cracker (KIT/UNATA)Figure 14: Cocos
Grater (KIT)

Figure 15: Roller Mill (KIT/UNATA)

As no motorized equipment is required, it is particularly
suitable as a women's activity, enabling the maximum of the value added to be
retained by the processors themselves. The dry process consists of the five
process-steps shown in flowsheet 5.

Flowsheet 5 Dry Process for Processing
Oil seeds (General Flowsheet)

1) decortication: to prepare a rawmaterial for further
processing with the highest possible oil content,

2) size reduction: to obtain a well crushed material, with still
some coherence, to facilitate filtration during pressing but to avoid the
pressing-out of fine material with the oil. The best way to crush is between
rollers into very fine flakes, preferably thinner than 0.1 mm. Particles to
start with should be smaller than 5 mm diameter.

3) cooking: to prepare a mass in which the oil is present in a
form that it can relatively easily be pressed out. During cooking the following
processes take place:

- weakening of the cell walls,- enaturing of proteins,
destabilizing the oil emulsion, the original form in which the oildroplets are
present in the cells,- coalescence (flowing together) of micro oil droplets
into larger ones, - diminishing of viscosity because of higher
temperature.Cooking is a process in which temperature, moisture and time
play an important role.

4) pressing: to separate the oil from the rest of the seed. To
be able to use a press with the lowest possible maximum pressure, size reduction
and cooking should be carried out with great care. For most oil seeds optimal
conditions are achieved by pressing at about the same moisture content as that
of the original rawmaterial. In that case, the maximum pressure should be 60
kg/cm². Higher pressures have, in that case, little effect, as the mass
will be extruded through the holes in the press cage. Oil recoveries are good,
while equipment remains simple. At higher maximum pressures either cage contents
become inefficiently small or the equipment becomes much too complicated and too
expensive.

5) drying of the oil: to prepare a dry and pure oil, fit for
long-term storage. Oil should be dry and free of impurities. The oil has
therefore to be heated to 130°C to remove all traces of moisture. After
leaving the oil to stand for a few days, the impurities will have settled and
pure oil can be decanted. The oil should be filled to the top in clean and dry
bottles or tins, and stored in a dark and cool place. Oil treated in this way
has a shelf- life of at least 6 months.

KIT has developed unsophisticated equipment to carry out the dry
process, completely by hand. It can be used to process oil seeds at the village
level as: groundnuts, sunflowerseed, palm kernels, coconuts, sesame seed, rape-
seed, castor seed and shea nuts.

5 Oil content and recovery are not given as a percentage, but as
kg per 100 nuts!

A grater for grating fresh coconut (a drill type) and a
different type for half dried copra (disc type, see Figure 14) are under
development. Originally, hydraulic hand presses were used, based on hydraulic
lorry jacks.

Figure 17: Spindle Press (UNATA)

It appeared, however, that already at a maximum pressure of 60
kg/cm² good oil recoveries could be obtained and therefore the UNATA
spindle press was adopted. The press was redesigned to meet the requirements and
has been put into production (see Figure 17). Only for shea nut processing does
this press not give a good oil recovery, as a maximum pressure of 120
kg/cm² is required. Up to now, only the hydraulic press, designed for the
GTZ/GATE project in Mali, can be efficiently used to process shea nuts.

However, a spindle press for shea nut processing is under
development. The performance of the KIT process, using the UNATA spindle press,
is given in Table 9.

In Tanzania, IPI has developed equipment for processing
sunflowerseed, following the same process. The equipment is described in Chapter
5.1.2.

IPI has carried out detailed research on the effect of the
different process steps described above on the overall press efficiency; i.e.
the oil recovered as a percentage of the oil present in the rawmaterial. The
results are illustrated in Figure 18.

Figure 18: Oil Yield as Determined by
the Number of Machines Used in the Process for Sunflower Seeds (IPI)

For its hand-operated system, IPI advises boiling the crude oil
with salt (2 %) and water (10 %), decanting and filtering through a cloth. The
performance of the IPI system is summarized in Table 10.

Table 10: Typical Performance of IPI
Hand-operated System

In Chapter 3, details are given on the sunflowerseed processing
project in Zambia and on the GTZ/GATE project in Mali. The economic aspects of
these activities are worked out in Chapter 4.

Oil-Expellers

The dry process cannot only be executed by mechanical or
hydraulic presses, but also by continuously operating screw presses, generally
named oil expellers. An oil expeller consists of a perforated cage in which a
tapered screw turns. The screw is tapered in a way that the free space between
the centre of the screw and the cage gradually becomes smaller to the end of the
cage. With this system, very high pressures can be exerted on the material to be
pressed.

The rawmaterial has to be prepared in principle by
decorticating, crushing between rollers and cooking. Depending on the type of
machine, however, some oil seeds can be processed even when not decorticated.
Expellers are usually driven by petrol or diesel engines or electric motors but
can also be run on animal or water power.

The performance of an expeller developed especially for
processing on a small scale is presented in Table 11. Other small expellers give
comparable results.

Table 11: Typical Performance of Oil
Expeller MINI 40 ¹,²

1 Manufactured by Simon-Rosedowns, Hull, England.

2 Figures from the manufacturer for one pressing only. More oil
can be produced by pressing a second time.

The performance of an expeller developed for processing in one
step (so-called "deep" pressing) is given in Table 12.

Table 12: Typical Performance of Oil
Expeller MRN (AP VII) ¹,²

1 Manufactured by Maschinenfabrik Reinartz, Neuss, F.R.G.

2 Figures from the manufacturer. Even higher recoveries can be
obtained with proper preparation including heating.

In the above tables, all data on performances are those given by
the manufacturers and may have been determined under favourable conditions.
After some time of intensive use, the oil recovery of expellers usually declines
until an overhaul becomes necessary. Furthermore, it should be kept in mind,
that oil expellers require considerable maintenance and repair, for which
expensive spare parts are required. Generally, conditions in villages are such
that it is very difficult to run expellers economically, if they can be kept
running at all! Expellers are generally found in towns, e.g. in East Africa,
where they are sometimes made available as service mills.

More details on expellers as alternative oilseed processing
equipment are given in Chapters 3, 4 and 5.

2.3 District level

Oil processing at the district level (in the sense of a group of
a few villages), offers interesting possibilities.

At this level, however, the technical performance of the
equipment is only one side of the picture and, in fact, less problematic than
the management of such a project. Important aspects include:

- the ability of the people concerned to organize themselves (in
a cooperative or in a private business),- the ability to handle funds,-
the ability to take care of the rawmaterial supply and- the marketing of the
products.

Nevertheless, centralization can contribute considerably to the
feasibility of the more sophisticated technology as already described for the
village level. For instance in the case of oil palm fruit processing, mechanized
equipment, such as the TCC pounding machine and certainly the CALTECH and COLIN
expellers, need to be well utilized owing to the high investments involved.
Where the infrastructure is well developed and the distances not too far for
economic transportation, a combination of the raw material resources of several
villages and a centralized processing facility could be a realistic alternative
to processing at the village level.

In that case, one could think of a well engineered unit,
equipped with:

In the case of oilseed processing, an expeller - often to be
imported - could become a possibility, provided that technical prerequisites are
fulfilled, such as the availability of spare parts and the necessary skills for
maintenance and repair.

Apart from the technical aspects, it should be kept in mind that
such highly mechanized technologies are in principle:

- capital intensive,- labour-saving,- economically
sensitive to bad harvests and falling oil prices, and- socially geared to
the use by men instead of women.

A considerable decline in employment opportunities at the
village level (particularly for the women) might therefore be the effect of a
larger scale oil processing operation at the district level.

Although such units might look attractive from the technical
point of view (see details in Chapter 5), the setting up of: centralized units
cannot be recommended as long as there are still doubts as to the possibility of
finding appropriate solutions for the technical as well as the man agement and
more human-oriented problems.